The scandal has thrown the Argentina camp into crisis days before their final Tri-Nations match against Australia in Sydney on Saturday.
The Argentine Rugby Union (UAR) said its board had met urgently after revelations of the players’ “discriminatory” posts between 2011 and 2013.
“The Argentine Rugby Union strongly repudiates the discriminatory and xenophobic comments published by members of the Los Pumas squad on social networks,” the union said.
“Although the messages were expressed between 2011 and 2013… the Argentine Rugby Union condemns any expression of hatred and we consider it unacceptable that those who express them represent our country.”
The UAR said it had requested Pumas staff to propose a new captain to the board and have the players stood down pending a “disciplinary process”.
The players’ social media accounts were closed on Tuesday but screenshots of past posts which disparaged black people and people from other South American nations circulated widely.
Argentinian media published screenshots of apologies posted on social media by the three players.
“I am very ashamed,” Matera said.
“Sorry to all those who were offended by the barbarities that I wrote. At that time I never imagined who I was going to become. Today I have to own what I said nine years ago.
“I apologise also to my family and my team for what they are going through because of my actions and thanks to the people who love me for their support.”
Matera, a 27-year-old flanker, and veteran lock Petti were in the starting 15 for Argentina’s 38-0 defeat by New Zealand in the Tri-Nations match in Newcastle on Saturday, with hooker Socino in the reserves.
Only weeks ago Matera was the toast of the rugby world for his brilliant performance in leading his team to a 25-15 win over the All Blacks in Sydney, Argentina’s first victory over the New Zealanders.
However, their Tri-Nations campaign has quickly gone downhill.
Following Saturday’s defeat, Matera apologised to fans in a video posted on the Pumas’ Twitter account after the players were criticised for not doing enough to pay tribute to soccer icon Diego Maradona, who died last week.
Matera’s discriminatory posts then resurfaced on Twitter in response to that apology.
A team spokesperson said the Pumas had cancelled all media activities on Tuesday and referred Reuters to the UAR’s statement.
Wallabies prop Allan Alaalatoa said Matera’s absence would be a big blow to the Pumas.
“Pablo being their captain is going to be a huge loss, I’m sure,” he said.
“We’re really unclear with what’s going to happen on their end.” DM
"Thou almost make me waver in my faith to hold opinion with Pythagoras" ~ Shakespeare, Merchant of Venice